Two-stage plunger lift device



April 27, 1954 D. G. KNox Two-STAGE PLUNGER LIFT DEVICE l2 Sheets-Sheetl Filed March 5, 1951 .5 my TM N my V m ma m M M u wA April 27, 1,954

Filed March 5, 1951 D. G. KNox 2,676,547

TWO-STAGE PLUNGER LIFT DEVICE 2 Sheets-Sheet 2 I z g far/ga. s. g I

28 /49 4o /2747 '5' se 5 so 5@ i 48 2 v INVENTOR. I g D 20x/,qm G'.,eA/0x i BY Y so o, E .a O M Patented Apr. 27, 1954 TWO-STAGE PLUNGERLIFT DEVICE Donald G. Knox, Long Beach, Calif., assignor to The NationalSupply Company, Pittsburgh, Pa., a corporation of PennsylvaniaApplication March 5, 1951, Serial No. 213,885

(Cl. ID3- 46) 14 Claims.

This invention relates to apparatus for raising oil or other fluid fromwells, and is particularly directed to improvements in plunger liftdevices of the general type shown in my United States Patent No.2,508,174.

The principal object of the present invention is to provide plunger liftapparatus capable of increased production capacity without changing thesize of the eduction tubing.

Another object is to reduce the amount of in- `iection gas required perbarrel of oil produced.

Another object is to provide a dual or twostage plunger lift apparatusin which a first plunger travels from the bottom of the eduction tubingto a midway point and then returns to the bottom while the secondplunger picks up the fluid unloaded at the midway station and carries itto the surface of the ground, with both plungers moving simultaneously.

In plunger lift devices now in use, a single plunger travels the fulllength of the eduction tubing from the bottom of the well to the groundsurface. In present eld practice a single plunger lifting fluid fromeight thousand feet can bring up a maximum of about one hundred ftybarrels per day. It the depth is ten thousand feet only about onehundred twenty live barrels per day can be produced. The reason for thelower rate of production is that a longer time is required for theplunger to travel the greater distance, and also, at near maximumproduction rates the number of cycles per day are reduced because of thegreater height of fluid column in the eduction tubing that the plungermust fall through each time it returns to the bottom of the fj,

tubing string.

Other factors limiting the production rate are the height, density andviscosity of the fluid column itself. As the plunger travels to thesurface with its load of fluid at an estimated average speed of onethousand feet per minute, gas and oil are entering into the lower end ofthe eduction tubing. It is the slippage or passage of gas through theincoming well iiuid that makes it possible for the plunger to continueits trip to the surface. if the column of iluid in the lower end of theeduction tubing becomes tno high the propelling gas fails to breakthrough and the plunger will slow down or stop. Within limits pressureand volume of the gas supplied from the surface into the well casing canbe increased to break through high iiuid columns in order to maintainaverage plunger speed. The upper limit is approached when flowvelocities of the gas operation.

In accordance with my invention, the production rate on deep wells isincreased by using a plurality of plungers within the same eductiontube, each of the plungers travelling only part of the length of theeduction tube. Assuming that two plungers are used, the lower plungerdischarges its load at a midway station about half way up from the lowerend of the eduction tube. The upper plunger carries the load from themidway station to the surface. The cycle time is about one-half thatrequired for a single plunger to complete the round trip from the bottomof the tubing to the surface. The fluid loads for each of the dualplungers is about half the corresponding load for a single plunger, andsplitting the load permits a more rapid rate of upward travel of theplungers. Furthermore, the dual plungers take less time to pass downthrough the shorter fluid columns. The ratio of injected gas to oilproduced may be reduced in certain wells where maximum production ratesare not required. This may be accomplished because the stored up gasenergy that is trapped below the second plunger at the time the well isshut in is fully utilized in lifting a fluid load each cycle.

In the drawings:

Figure la is a side elevation partly in section showing the surfaceequipment of a plunger lift device embodying my invention and alsoshowing the upper portion of the well casing and eduction tubing.

Figure 1b is a sectional view constituting a continuation of the lowerend of Figure la and showing the midway station at the upper end of thetravel of the lower plunger and the lower end of the travel of the upperplunger.

Figure 1c is a sectional elevation constituting an extension of thelower end of Figure 1b and showing the lower end of the bore hole andthe lower end of the plunger lift device.

Figure 2 is a sectional View taken substantially along the line 2 2 ofFigure 1a showing a preierred form of construction of one of theplungers.

Figures 3a and 3b are sectional elevations taken substantially along thelines 3a-3a of Figure 1b. Figure 3b is a continuation of the lower endof Figure 3a.

Figure 4 is a sectional plan view taken substantially along the line tci of Figure 3a.

Referring now to the drawings, the sectional well casing iii extendsinto the bore hole and the means of a nipple I@ to the master gate ortrap valve I5. The valve i5 is in turn connected to the stack assemblygenerally designated I6. This assembly i6 includes a spring mountedspear il of the type described in my copending application, Ser. No.106,579.

The lower` end of the eduction tubing I3 is connected to a footpiece i8from which is suspended a perforated liner pipe i9. Oil and gas enteringthe eduction pipe i3 pass inward through the perforations in the linerpipe I9. A lower plunger generally designated 2.@ travels in the lowerportion of the eduction tubing i3 while an upper plunger generallydesignated 2I travels in the upper portion of the same eduction tubingI3. A barrier device generally designated 22 is anchored within the`eduction tubing at a midway station located about hali way from thelower end of the eduction tubing to the surface. barrier device 22 tothe surface and returns while the lower plunger 2t travels from thelower end oi the eduction tubing i3 to the barrier device 22 andreturns.

The plungers 2e and 2l may be substantially "f plungers each comprise abody 23 having spaced sets of radially movable sealing elements 2dadapted to seal against the inner surface 25 of the eduction tubing E3.For clarity of illustra tion the couplings joining adjacent sections ofthe tubular eduction pipe are omitted, but it will be understood thatthe construction of the radially movable sealing devices 24 is such thatthey pass over1 the joints between adjacent sections of the eductionpipe without interference or possibility of hanging up. The body 23 isprovided with a central passage 26 extending from end to end, and thispassage may be closed by means of the vertically movable poppet-typevalve 2l which has a head 2S adapted to seal against the seat 2S. Thelower end of the valve stem 30 projects below the lower end of the bodyi3. When the valve is in open position as shown in Figure 2, the plungerfalls downwardly through the eduction tubing i3, and any fluid in theinterior oi the eduction tubing passes upward through the r passageway2e to permit the plunger to fall through the fluid. When the valve 2 isclosed, the plunger is lifted within the eduction tubing i3 by thepressure oi the gas below the plunger, and the lowering of gas pressureabove it. lowering of the gas pressure in the eduction tubing occurswhen the motor valve (not shown) in the discharge line is opened. Amotor valve of this type is shown in my Patent No. 2,503,174, grantedMay 16, 1950.

The barrier device 22 may be anchored at any selected point within theeduction tubing I3 and may be lowered on a wireline extending from thesurface into position. As shown in the draw-v ings, this barrier deviceincludes a tubular mann drel 3l having an externally tapered surface 32.A plurality oi" wedge slips 33 are mounted on the surface 32 and areprovided with wicker teeth 34 for engaging the inner surface 25 of theeduction tubing I3. A supporting arm 35 extends downwardly from each ofthe wedge slips 33. The lower end 36 of each arm is secured relative toa collar 3l. The upper end 38 or a coil spring 39 is xed on the lowerextension t0 of the collar 3l'. The lower` end of the spring 39 is fixedto The upper plunger 2i travels from this the line.

4 the upper end of the spear tube lil. From this description it will beunderstood that the spear iii, spring 3S, and collar 3'! are suspendedfrom the slips 33 which engage the inner surface of the eduction tubingI3.

The tapered mandrel 3i is supported within the tapered bore lli. of theslips 33 and the upper end of the mandrel is provided with a flange orhead i3 which is engaged by a plurality of spring iingers lill extendingdownwardly from the collar '65. Threads G6 connect the collar i5 with asealing device generally designated il which seals against the innerwall 'E5 of the eduction tubing I3. While any conventional or desirableform of seal may be employed, I have found that one of the sealing unitsof the type employed on the plungers 2e and 2I may be used to goodadvantage. Accordingly, the sealing device il includes a tubular body 48having a plurality of longitudinally extending radially spaced slots i0and a circumferential groove 5i! intersecting the slots. Radiallymovable bars 5l are positioned within the slots 9, and ring segments 5Eare mounted in the groove 50. The central portions of the bars and thering segments cooperate to form an uninterrupted circular seal with theinterior ol' th-e eduction tubing I3.

Threads 53 connect the upper end or the tubular body d3 to the sleeve54. The sleeve l is connected by threads 5i? to the valve cage 55. Aball valve 5l is mounted within the cage Eil and normally rests on theupper end of the annular seat 53. A coil spring 59 maintains the valveseat in engagement with the tapered shoulder 35 on the cage 56. The cageis provided with a central chamber 6I. A bar 62 mounted on the cageextends diametrically across the chamber ti to limit upward travel ofthe ball 52'. An upper extension 63 on the cage pre1" -i mounting forthe lower end ttl of the coil s The upper end of the coil spring e5 caia bumper 6G against which the valve stem 3G on the upper plunger 2lrests when the plunger 2i mounted at the upper end of a Coil spring unethe lower end of this coil spring is mounted the support 59 which isdetachably connecte the foot-piece I by means of the spring le. Thebarrier device 22 is lowered into L. tion on a wire line and ispreferably lowers two sections in order to reduceY the weight The lowersection comprising the in drei 3i, slip assembly, spring 30 and spear diare lowered rst. The slips 33 are set by suddenly increasing the rate ofdownward travel. The upper section comprising the bumper 56, 65, valvecage 55, body l? and collar z lowered. The two sections are joined whenthe spring fingers 44 engage the fishing neck at the upper end of themandrel Si In operation, well fluid enters the lower end of the eductiontubing ill through the perfor in the liner pipe il Well fluid passesthrough the interior of the support Eid interior of the eduction tubing.Forma` in the annulus 9 between the easing il e tion tubing i3 forcesthe column of upwardly within the eduction tubing it. gas pressurewithin the annelus t may be supplemented by gas pumped into the annulusfrom the surface through the side outlets in the casing head I I, ifdesired.

Assuming that the lower plunger 2@ is dropping by gravity through acolumn of well duid in the lower end of the eduction tubing it, the

plunger continues its downward movement until the valve stem 3B engagesthe spring mounted bumper 6l. This closes the valve 2l in the plunger20. The pressure in the eduction tubing below the plunger 2i! thereuponraises the plunger 20 to lift a column of well duid above it. Theplunger and its load of well uid continues upward until the spear diextends into the central opening 26 in the plunger and mechanicallyengages the upper end of the valve head 28 to open the valve. The loadof well iluid above the plunger 2li passes upward through the interiorof the hollow collal` 3l, hollow mandrel Si, collar 45, hollow body i8and past the check valve 5l into the eduction tubing i3 above thelocation of the barrier device 22. The seal aiforded by the bars 5| andring segments 52 prevents the well iiuid from leaking downwardly aroundthe exterior of the barrier device. When the valve 2l in the lowerplunger 2Q is opened, the Iplunge: 2G again drops by gravity downwardtoward the lower end of the eduction tubing I3 to begin another cycle ofoperations.

The upper plunger 2l drops by gravity through the upper portion of theeduction tubing and down through the column of well fluid previouslyraised by the lower plunger 2Q. valve stem 35i engages the springmounted bumper il@ to close the valve and arrest downward movement ofthe plunger 2|. Pressure within the eduction tubing I3 below the plunger2l then raises the plunger upwardly toward the surface, carrying theload of well fluid above it. When the plunger El approaches the surface,the column of well fluid above it passes out through discharge pipes lland l2 connected to the stack assembly it. The spring mounted spear ilmechanically ergages the valve head 23 to open the valve, and theplunger 2l thereupon descends by gravity down toward the barrier device22 to begin a new cycle. From the above description it will beunderstood that the upper and lower plunger-s 2li and 2l operatesimultaneously, and that each travels back and forth in its respectiveportion of the eduction tubing i3. While only plungers have been shownand described, more an two can be employed in the same eduction t bingif desired.

ln the event that it should be desirable to reduce the height of theiiuid column above the check valve 5l, gas under pressure can be appliedto the interior of the tubing at the well head. When a pressure ofsuiiiciently great intensity is reached, the spring 59 is compressed,allowing the seat 53 to move away from its sealing shoulder 6E, therebypermitting downwaroL now of duid in the tubing past the check valve.

lf it should become necessary to remove the plungers and barrier device22 from the well for servicing or cleaning, or for any other reason, theupper plunger 2l may be trapped at the sur-- face by closing the valvel5 and thereafter an overshot device oi conventional forni may belowered from the surface on a wire line to engage the bumper 65. Anupwardly directed force applied to the bumper et raises the spring valvecage 56, hollow body t8, sleeve lid, and mandrel 3i. Raising of themandrel 3i releases the slips 3S from contact with the inner wall o theeduction tubing iii.l The ring 'i3 which cncircles the slip support arms35 is fined to the mandrel by means of iingers 'it located betweenadjacent arms 35. VWhen the mandrel moves upwardly the shoulder l5 onthe ring it. engages the abutments 'i6 on the wedge slips 33 so that twothe wedge slips 33, collar 31, spring 39 and spear lll are withdrawnfrom the eduction tubing i3 along with the mandrel 3|.

When the barrier device 22 has been lifted to the surface on the wireline, it may be set aside and the wire line and overshot again run intothe hole to engage the bumper 61. An upwardly directed force applied tothe bumper 6l by means of the overshot tensions the spring t8 and servesto disengage the spring fingers lil on the support 69 from the footpieceI8. The parts El, 68, 6@ and lil are then withdrawn on the wire line.

Having fully described my invention, it is to be understood that I donot wish to be limited to the details herein set forth, but my inventionis of the full scope of the appended claims.

I claim:

l. in a multiple-stage plunger lift device :for raising well iiuid in aneduction tubing, the combination of: a barrier device adapted to befixed in said eduction tubing, the barrier device having a passagewayextending therethrough, a iirst plunger adapted to travel in theeduction tubing from the lower end thereoic to the barrier device toraise a load of well fluid through sai-l passageway into the eductiontubing above the barrier device, a second plunger adapted to travel inthe eduction tubing from the barrier device to a location in theeduction tubing spaced above the barrier device for raising well iiuidupwardly from the barrier device, each of the plungers having apassageway extending longitudinally therethrough and each having anupwardly closing valve for closing the passageway, and means at thelower end of the eduction tubing constituting the sole means forintroducing niotive fluid into the eduction tubing.

2. in a multiple-stage plunger lift device for raising well fluid in aneduction tubing, the combination of: a barrier device adapted to benrqed in said eduction tubing, the barrier device having a check valvepreventing low of iiuid downwardly through the barrier device, a rstplunger adapted to travel in the eduction tubing from the lower endthereof to the barrier device to raise a load o well huid through thecheck valve into the eduction tubing. above the barrier device, a secondplunger adapted to travel in the eduction tubing from the barrier deviceto a location in the eduction tubing spaced above the barrier device forraising well fluid upwardly from the barrier device, each of theplungers having a passageway extending longitudinally therethrough andeach having an upwardly closing valve for closing the passageway, andmeans at the lower end of the eduction tubing constitilting the solemeans or introducing motive iiuid into the eduction tubing.

3. In a multiple-stage plunger lift device for raising well fluid in aneduction tubing, the coinbination of: a barrier device in said eductiontubing, means including wedge slips on the barrier device engageablewith the inner surface or the eduction tubing for releasably anchoringthe barrier device in the eduction tubing, the barrier device having acheck valve preventing iow of fluid downwardly through the barrierdevice, a rst plunger adapted to travel in ihe eduction tubing from thelower end thereof to the barrier device to raise a load or" well fluidthrough the check valve into the eduction tubing above the barrierdevice, a second plunger adapted to travel inthe eduction tubing fromthe barrier device to a location in the eduction tubing spaced above thebarrier device for raising well fluid upwardly from the barrier device,each of the plungers having a passageway extending longitudinallytherethrough and each having an upwardly closing valve for closing thepassageway, and means at the lower end of the eduction tubingconstituting the sole means for introducing motive iuid into theeduction tubing.

4. In a multiple-stage plunger lift device for wells, the combinationof: an eduction tubing, a barrier device xed in said eduction tubing,the barrier device having a passageway extending therethrough, a firstplunger in the eduction tubing traveling from the lower end oi theeduction tubing to the barrier device to raise a load of Well fluidthrough said passageway into the eduction tubing above the barrierdevice, a second plunger in the eduction tubing travelling from thebarrier device to a location in the eduction tubing spaced above thebarrier device for raising well iluid upwardly from the barrier device,each of the plungers having a passageway extending longitudinallytherethrough and each having an upwardly closing valve for ciosing thepassageway, and means at the lower end of the eduction tubingconstituting the sole means for introducing motive fluid into theeduction tubing.

5. In a two-stage plunger lift device for wells, the combination of aneduction tubing, a barrier device fixed in said eduction tubing, thebarrier device having a passageway extending therethrough, a lowerplunger in the eduction tubing adapted to travel from the lower end oithe eduction tubing to the barrier device to raise a load of well fluidthrough said passageway into the eduction tubing above the barrierdevice, an upper plunger in the eduction tubing adapted to travel fromthe barrier device to the upper end of the eduction tubing for raisingwell duid to the surface, each of the plungers having a sagewayextending longitudinally therethrough and each having an upwardlyclosing valve closing the passageway, and means at the lower end of theeduction tubing constituting the sole means for introducing motive fluidinto the eduction tubing.

6. In a two-stage plunger lift device for wells, the combination of: aneduction tubing, a barrier device iixed in said eduction tubing, thebarrier device having a check valve preventing iiow of iiuid downwardlythrough the barrier device, a lower plunger in the eduction tubingtravelling from the lower end of the eduction tubing to the barrierdevice to raise a load of well fluid through the check valve into theeduction tubing above the barrier device, an upper plunger in theeduction tubing traveling from the barrier device to the upper end ofthe eduction tubing for raising well fluid to the surface, each ci theplungers having a passageway extending longitudinally therethrough andeach having an upwardly closing valve for closing the passageway, andmeans at the lower end of the eduction tubing constituting the solemeans for introducing motive fluid into the eduction tubing.

7. In a two-stage plunger lift device for wells, the combination of z aneduction tubing, a barrier device in said eduction tubing, meansincluding wedge slips on the barrier device engaging the inner surfaceof the eduction tubing for releasably anchoring the barrier device inthe eduction tubing, the barrier device having a check valve preventingow of uid downwardly through the barrier device, a lower plunger theeduction tubing travelling from the lower end of the eduction tubing tothe barrier device to raise a load of well uid through the check valveinto the eduction tubing above the barrier device, an upper plunger inthe eduction tubing travelling from the barrier device to the upper endof the eduction tubing for raising well fiuid to the surface, each ofthe plungers having a passageway extending longitudinally therethroughand each having an upwardly closing valve for closing the passageway,and means at the lower end of the eduction tubing constituting the solemeans for introducing motive duid into the eduction tubing.

8. In a multiple-stage plunger lift device for raising well uid in aneduction tubing, the combination of: a barrier device in said eductiontubing, means including wedge slips on the barrier device engageablewith the inner surface of the eduction tubing for releasably anchoringthe barrier device in the eduction tubing, the barrier device having acheck valve preventing riow of fluid downwardly through the barrierdevice, a rst plunger adapted to travel in the eduction tubing from thelower end thereof to the barrier device to raise a load of well iiuid ththe check valve into the eduction tubing above the barrier device, abumper element resll' tly mounted on the barrier device for a ngdownward movement of the rst plunger, a second plunger adapted to travelin th euction tubing from the barrier device to a location in theeduction tubing spaced above the barrier device for raising well iiuidupwardly from the barrier device, each of the plungers having apassageway extending longitudinally therethrough and each having anupwardly closing valve for closing the passageway, and means at thelower end of the eduction tubing constituting the sole means forintroducing motive into the eduction tubing.

9. For use in multiple-stage plunger lift apparatus employing aplurality of swab plungers travelling freely within a single eductiontubing, the combination of: a barrier device inserta-ble into theeduction tubing from the upper end thereof, means on the barrier devicefor releasably anchoring it within the eduction tubing, the barrierdevice having a passageway extending therethrough, a check valve in seidpassageway preventing passage oi fluid downwardly in said passageway, abumper element resilient-ly mounted on the barrier device for arrdownward movement of an upper plunger, an element resiliently mounted onthe l; device for arresting upward movement ci a lewe plunger.

10. For use in multiple-stage plunger liit apparatus employing aplurality of swab plungers travelling freely within a single eductiontubing, the combination of: a barrier device insertable into theeduction tubing from up end thereof, means including wedge slips on i, orier device engageable with the inner si face of the eduction tubing forreleasably anchoring the barrier device in the eduction tub fr, the

preventing passage of iluid downwardiy passageway, a bumper elementmounted on the barrier device for ar downward movement of an upperplunger an element resiliently mounted on the barrier device forarresting upward movement of a lower plunger.

11.For use in multiple-stage plunger lift apparatus employing a,plurality of valved swab plungers travelling freely within a singleeduction tubing, the combination of: a barrier device insertable intothe eduction tubing from the end thereof, means including wedge slips onthe barrier device engageable with the inner sur- `lace of the eductiontubing for releasably anchoring the barrier device in the eductiontubing, means establishing a seal between the barrier device and theinner surface of the eduction tubing, the barrier device having apassageway extending therethrough, a check valve in said passagewaypreventing passage o fluid downwardly in said passageway, a bumperelement resiliently mounted on the barrier device for arresting downwardmovement of an upper plunger and for closing its valve, and a spearelement resiliently mounted on the barrier device for arresting upwardmovement of a lower plunger and for opening its valve.

12. Multiple-stage plunger lift apparatus having in combination: aneduction tubing, a pair of z b plungers travelling freely within theeduction tubing, a barrier device positioned within the eduction tubingbetween said plungers, means on the barrier device for releasablyanchoring it within the eduction tubing, the barrier device liaving apassageway extending therethrough, a check valve in said passagewaypreventing passage of fluid downwardly in said passageway, a bumperelement resiliently mounted on the barrier device for arresting downwardmovement of one of the plungers, and an element resiliently mounted onthe barrier device for arresting upward movement of the other plunger.

13. Multiple-stage plunger lift apparatus 'naving in combination: aneduction tubing, a pair oi swab plungers travelling freely within theeduction tubing, a barrier device positioned within the eduction tubingbetween the plungers, means including wedge slips on the barrier deviceengageable with the inner surface of the eduction tubing for releasablyanchoring the barrier device in the eduction tubing, the barrier devicehaving a passageway extending therethrough, a check valve in saidpassageway preventing passage of fluid downwardly in said passageway, abumper element resiliently mounted on the barrier device for arrestingdownward movement of one of the plungers, and an element resilientlymounted on the barrier device for arresting upward movement of the otherplunger.

14. Multiple stage plunger lift apparatus having in combination: asingle eduction tubing, a pair of swab piungers travelling freely withinsaid single eduction tubing, each plunger eing tubular and having avalve near the lower end thereof adapted to move upwardly to closedposition, a barrier device positioned within the eduction tubing betweenthe plungers, means on the barrier device for releasably anchoring itwithin the eduction tubing, the barrier device having a passagewayextending therethrough, a check valve in said passageway preventingpassage of iiuid downwardly in said passageway, a bumper elementresiliently mounted on the barrier device for arresting downwardmovement of an upper plunger and for closing its valve, and a spearelement resiliently mounted on the barrier device for arresting upwardmovement of a lower plunger and for opening its valve.

lteferences Cited in the file 0f this patent UNITED STATES PATENTSNumber Name Date 971,612 Holliday Oct. 4, 1910 1,547,025 Callahan July21, 1925 2,001,551 Scott 1 May 14, 1935

